Synchroma grande spec. nov. (Synchromophyceae class. nov., Heterokontophyta): An Amoeboid Marine Alga with Unique Plastid Complexes

Chromist algae including the Heterokontophyta are supposed to have evolved monophyletically by secondary endosymbiosis from a eukaryotic host cell that engulfed a eukaryotic red alga. The red algal endosymbiont was then reduced to a secondary plastid surrounded by four enveloping membranes. On the b...

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Bibliographic Details
Published in:Protist 2007-07, Vol.158 (3), p.277-293
Main Authors: Horn, Susanne, Ehlers, Katrin, Fritzsch, Guido, Gil-Rodríguez, María Candelaria, Wilhelm, Christian, Schnetter, Reinhard
Format: Article
Language:English
Subjects:
Algal Proteins - genetics
amoeboid alga
Cell Membrane - ultrastructure
Chloroplasts - ultrastructure
Chromista
DNA, Algal - chemistry
DNA, Algal - genetics
DNA, Ribosomal - chemistry
DNA, Ribosomal - genetics
Eukaryota - classification
Eukaryota - genetics
Eukaryota - ultrastructure
Genes, rRNA
Heterokontophyta
Marine
Microscopy, Electron, Scanning
Microscopy, Electron, Transmission
Molecular Sequence Data
Phylogeny
Pigments, Biological - biosynthesis
Plastids - ultrastructure
Ribulose-Bisphosphate Carboxylase - genetics
RNA, Algal - genetics
RNA, Ribosomal, 18S - genetics
secondary endosymbiont
Sequence Analysis, DNA
Sequence Homology, Nucleic Acid
Synchroma
Synchroma grande
Synchromophyceae
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Summary:Chromist algae including the Heterokontophyta are supposed to have evolved monophyletically by secondary endosymbiosis from a eukaryotic host cell that engulfed a eukaryotic red alga. The red algal endosymbiont was then reduced to a secondary plastid surrounded by four enveloping membranes. On the basis of the amoeboid marine alga Synchroma grande gen. et spec. nov., the Synchromophyceae are described here as a new class of Heterokontophyta. Their taxonomic position is characterized by 18S rRNA and rbcL gene phylogenies, morphology, and pigment composition. The so far unique feature of the Synchromophyceae is the occurrence of conspicuous chloroplast complexes representing multiplastidic red secondary endosymbionts. In these remarkable secondary endosymbionts, several primary chloroplasts are aggregated in a common periplastidial compartment and are collectively enveloped by an additional outer membrane pair. The discovery of this novel plastid morphology is highly relevant for research on algal evolution and is discussed in terms of the postulated monophyletic origin of Chromista.
ISSN:1434-4610
1618-0941
DOI:10.1016/j.protis.2007.02.004